Synthesis of MOFs

ABSTRACT

The present invention relates to the synthesis of a variety of metal organic frameworks (MOFs) using low temperature and solvents which are considered to be not particularly harmful to the environment. There is also provided novel MOFs which may be made by the desired processes.

FIELD OF INVENTION

The present invention relates to the synthesis of a variety of metalorganic frameworks (MOFs) using low temperature and solvents which areconsidered to be not particularly harmful to the environment. There isalso provided novel MOFs which may be made by the desired processes.

BACKGROUND TO THE INVENTION

Coordination polymers are a class of materials which are formed fromextended chains, sheets or networks of metal ions interconnected byligands.

Metal organic frameworks—MOFs—are a type of coordination polymer havingextended three dimensional framework structures and show great promisein a wide range of applications including gas storage/release andbacteria/infection control.¹ There is particular interest in porous MOFswith accessible coordinatively unsaturated metal sites since these havebeen shown to greatly enhance the gas storage-release profile.² Forexample, such sites are found in the honeycomb-like structure of theCPO-27 family^(3,4) (or MOF-74).⁵ These frameworks are constructed fromchains of edge-sharing metal-oxygen polyhedra (octahedra when hydrated,square pyramids when dehydrated) connected by 2,5-dihydroxyterephthalateunits. The large one-dimensional hexagonal channels permit easy accessto the coordinatively unsaturated sites upon activation (dehydration).Indeed, such materials possess excellent adsorption/release profiles formany harmful and biologically active gasses including NO, H₂S andCO₂.^(2,6,7) They also show useful antibacterial properties both intheir pristine and NO-loaded forms.

Metal organic frameworks possessing porous three-dimensional structures(such as CPO-27) are commonly and traditionally made via solvothermalroutes. These approaches have several drawbacks when considering largescale commercial synthesis, including:

-   -   1) Use of harmful and environmentally unattractive organic        solvents    -   2) High temperatures and long reaction times resulting in high        processing cost    -   3) Requirement for sealed and pressure-rated vessel

For example, MOFs constructed from chains of edge-sharing metal-oxygenoctahedra connected by 2,5-dihydroxyterephthalate units and possessing ahoneycomb structure were first reported by Dietzel et al.³ and Rosi etal.⁵ Both authors used solvothermal techniques to prepare Zn-, Co- andNi-containing analogues. For example, Dietzel et al. reported thesynthesis of Zn-CPO-27 by mixing a solution of 2,5-dihydroxyterephthalicacid in THF with an aqueous solution of Zn nitrate and aqueous sodiumhydroxide.⁴ The resulting mixture was heated in a sealed autoclave at110° C. for three days. A similar procedure (without sodium hydroxide)was also reported for the Co and Ni analogues.^(3,4) Rosi et al.employed a similar technique but with DMF as solvent and with a smallamount of propanol. Subsequently, the Mg and mixed metal Zn/Co analogueswere synthesised in a similar fashion from solutions of the acid linkerand metal sources in DMF/water/ethanol and DMF/water solutions,respectively.^(8,9)

Tranchemontagne et al.¹⁰ reported that various MOFs, includingZn-CPO-27, can be made at room temperature and ambient pressure bymixing solutions of the relevant linker and metal source. In oneexample, MOF-5 (constructed from Zn₄O units connected by1,4-benzenedicarboxylate struts) was prepared by mixing solutions of thelinker and Zn acetate in DMF at room temperate and in the presence oftriethylamine. Although the amine was added to aid deprotonation of thelinker, subsequent studies showed that it was not essential when usingZn. Zn-CPO-27 was synthesised in this way by replacing1,4-benzenedicarboxylate with 2,5-dihydroxyterephthalic acid (DHTP).While this work removes the requirement for high temperature andpressurised vessels, it should be noted that the syntheses still rely onthe use of the environmentally undesirable and hazardous organic solventDMF.

Similarly, Rosi et al reported the synthesis of Zn-based MOF-69A and-69B at room temperature by dissolving Zn nitrate and linker in DMF/H₂O₂with CH₃NH₂.⁵

The Cu-containing MOF HKUST-1 has been shown to form at room temperatureeither by mixing Cu acetate, 1,3,5-benzenetricarboxylic acid (BTC) andtriethylamine in a 1:1:1 mixture of DMF/EtOH/H₂O, or by adding asolution of BTC in EtOH to a solution of Cu acetate in H₂O/aceticacid.¹¹

The requirement to use organic solvents in conventional syntheses isdictated by the solubility of the acid linker. For example,2,5-dihydroxyterephthalic acid is insoluble in water but dissolves insolvents such as THF and trimesic acid is only slightly soluble inwater.

A coordination polymer formed between Zn and DHTP but with a differentstructure to CPO-27 was synthesised by Ghermani et al. at roomtemperature.¹² The material was prepared by adding an aqueous solutionof Zn sulphate to the neutralised linker in aqueous sodium hydroxide.However, the resulting structure is composed of linear chains and isnon-porous. It is therefore not expected to possess significant gasadsorption capacity.

Akhbari, K. and Morsali, A. J. Iran. Chem. Soc., 2008, 5(1), 48-56describe the structure and physical characteristics of a Ag(I) trimesatecoordination polymer, which is thought to be composed of linear chains.Although it is synthesised at room temperature, the process depends onthe use of flammable and toxic methanol. An alternative method ofpreparation of this material is described by Sun, D., Cao, R., Weng, J.,Hong, M. and Liang, Y., J. Chem. Soc., Dalton Trans., 2002, 291-292. Themethod is a small scale and lengthy lab process not conducive toindustrial application.

Methods of synthesising silver MOFs require either high temperatures andpressures (for example, Ding, B., Yi, L., Liu, Y., Cheng, P., Dong, Y-B.and Ma, J-P., Inorg. Chem. Comm., 8, 2005, 38-40) or low temperaturesand use of organic solvents (for example, WO 2007/094567 and WO2007/029902 of Yeong et al.).

It is an object of the present invention to provide a method of MOFsynthesis which obviates and/or mitigates one or more of theaforementioned disadvantages.

SUMMARY OF THE INVENTION

According to a first aspect, the present invention provides a method ofsynthesising a MOF of the form of M_(x)(L)_(y)(OH)_(v)(H₂O)_(w) wherein;

M is a metal or metalsL is a benzene polycarboxylate linker; andx is 1-10, y is 0.1-3, v is 0-2 and w is 0-14;the method comprising the step of providing a salt of L or an aqueoussolution thereof; andmixing this with a solution of a metal salt/source at a temperaturebetween 0° C. and 100° C., in order to obtain said MOF.

In some embodiments, x is 2-10, y is 0.8-1.2, v is 0-1 and w is 0-14.

In some embodiments, x is 2-4.

One or more of the water molecules may be present as ligands and formpart of the three dimensional network structure of the MOF. One or moreof the water molecules may be present as hydrating water molecules andbe bound to the network structure.

As will be understood by a skilled reader, one or more water moleculesmay be disassociated, for example so as to form a protanated “H₃O+”species and a coordinating OH⁻ ligand, together with a further watermolecule.

The total amount of water w of the MOF may vary depending on the degreeof hydration.

Hydroxide ligands may form part of the framework structure, and may becoordinated to more than one metal ion within the framework structure.

The method may comprise providing a water soluble salt of L, inparticular of DHTP.

The metal salt/source may be dissolved in water or may be dissolved in awater/co-solvent mixture.

By benzene polycarboxylate linker we mean a polydentate (for example di-or tridentate) linking ligand comprising a benzene ring and at least twocarboxylate groups and, optionally, one or more further substituents tothe benzene ring.

In some embodiments, L is a benzene dicarboxylate or a benzenetricarboxylate.

L may be a dihydroxy benxene dicarboxylate, in particular2,5-dihydroxyterephthalate (DHTP);

i.e. In some embodiments, L is

L may be 1,3,5-benzene tricarboxylate (BTC).i.e. In some embodiments, L is

M may be any metal or metals, but preferably Zn, Ni, Mn, Mg, Ag, Cu, Na.M may comprise Ca, Co, Fe. In embodiments comprising BTC, M ispreferably Ag.

The MOF may be of the form M₂M′_(z)(DHTP) (H₂O)₂.qH₂O; wherein q is0-12, z=0-8; and

M is one or metals selected from, and M′ is a further metal selectedfrom, the group Zn, Ni, Mn, Mg, Ag, Cu, Na.

The MOF may be of the form of M₂(DHTP)(H₂O)₂.qH₂O, where the number ofhydrating water molecules q is 0-12.

The MOF may be of the form of M_(x′)(BTC)_(y′)(OH)_(v′)(H₂O)_(w′) wherex′ is 1-5, y′ is 0.1 to 3, v′ is 0 to 2 and w′ is 0-5.

x′ may be in the range of 2-4, or 3-4. y′ may be in the range fromaround 0.5 to 2, or 0.8 to 1.2.

The MOF may be of the form of M_(x′)(BTC)_(y′)(OH)_(v′)(H₂O)_(w′) wherex′ is 3-4, y′ is 0.8 to 1.2, v′ is 0 to 1 and w′ is 0-5.

M may be Ag.

One or more metal ions, in particular may form part of the frameworkstructure, or may be present as charge balancing counter ions withinpores or channels and bound to the framework structure.

In some embodiments, the method comprises providing the sodium salt ofL, or alternatively the potassium or magnesium salt of L.

The salt of L may be water soluble (in water at or around pH 7) or maybe soluble in aqueous conditions above a threshold pH, for example aboveapproximately pH 6, pH 7 or in some embodiments above approximately pH10. The salt of L may be water soluble at a pH of below 14, or below 12or 10.

The method may comprise adding together a salt or a conjugate acid of Land a basic solution (and/or increasing the pH of water or an aqueoussolution in contact with the salt or conjugate acid of L) so as toprovide an aqueous solution having a sufficiently high pH to dissolvethe salt of conjugate acid of L and thereby provide an aqueous solutionof a salt of L.

The salt of L, or an aqueous solution thereof, may be synthesised inadvance, or may be synthesised as part of the method.

The salt of L, or aqueous solution thereof, may be prepared by additionof a compound comprising L (for example a conjugate acid or a salt of L,such as 2,5-dihydroxyterephthalic acid or trimesic acid-1,3,5-benzenetricarboxylic acid) and a base. For example, a water soluble salt ofDHTP may be prepared by addition of 2,5-dihydroxyterephthalic acid andsodium hydroxide, to produce a solution of the sodium salt of DHTP.

Typically, the method comprises adding the compound comprising L, or asolution or suspension of the compound comprising L, to a basicsolution, e.g. sodium hydroxide solution, to thereby provide an aqueoussolution of a salt of L.

In some embodiments, the method comprises inducing precipitation of thesalt of L from the solution of L in aqueous sodium hydroxide, or anothersuitable base.

Precipitation may be induced by addition of a solvent, such as ethanol,or by evaporation of water. In both cases the product can be purified byreflux in ethanol prior to further use. In one embodiment, the methodcomprises inducing precipitation of Na₂DTHP from an aqueous sodiumhydroxide, the solution comprising a molar ratio Na:DHTP preferably butnot restricted to 1-6, such as 2-4.

In other embodiments, the method comprises adding together an aqueoussuspension of an acid linker (e.g. trimesic acid), or an insoluble (orsubstantially insoluble) salt of L, and a basic solution. The solutionsare preferably added together in amounts so as to achieve a pH abovewhich the particles in the suspension dissolve, so as to form an aqueoussolution of the salt of L. The resulting aqueous solution of the salt ofL may then be added to the solution of a metal salt/source, or viceversa (i.e. the solutions may be added together in any order).

The basic solution may be any suitable basic solution, including forexample an aqueous solution of sodium or potassium hydroxide, or anaqueous solution of an organic base such as ammonia, trimethylamine ortriethylamine.

The MOF may be prepared by adding an aqueous solution of the salt of Lto a solution of the metal salt/source, typically in water orwater/co-solvent, under vigorous mixing such as brisk stirring, at thedesired temperature and for a desired length of time.

Alternatively, the MOF may be prepared by adding a solution of the metalsalt/source to an aqueous solution of the salt of L under vigorousmixing such as brisk stirring, at the desired temperature and for adesired length of time.

The aqueous solution of L may be prepared from the salt of L induced tobe precipitated from the basic solution, e.g. aqueous sodium hydroxidesolution. The precipitated salt of L may be further purified, forexample by recrystallisation or by refluxing in a second solvent, e.g.ethanol or propanol.

Alternatively, the MOF is prepared by adding a water soluble salt of L,metal salt/source, water and, optionally, co-solvent together directlyinto one vessel, and the mixture is vigorously mixed, e.g. stirredbriskly, at the desired temperature and for a desired length of time.

A water soluble salt of L, or an aqueous solution of L, may be madein-situ.

For example an acid linker (a conjugate acid of L, for example2,5-dihydroxyterephthalic acid) may be dissolved in aqueous metalhydroxide (e.g. sodium hydroxide) and the resulting solution added to asolution of the metal salt/source, preferably in water and optionally aco-solvent mixture, or vice versa.

In the above “in-situ” processes each mixture may be mixed e.g. stirred,vigorous at the desired temperature for a desired length of time beforethe product is obtained.

The metal salt/source can be any soluble metal salt, mixture of metalsalts or mixed metal salt, such as one or more nitrates, chlorides oracetates. In embodiments wherein L is DHTP, the metal salt/source ispreferably an acetate, to avoid formation of impurities. Where L is BTC,the metal salt/source is preferably a nitrate and preferably aco-solvent is not used.

The metal may be any metal or metals, but preferably selected from oneor more of Zn, Ni, Mn, Mg, Ag, Cu, Na.

The co-solvent can be any solvent such as any alcohol, THF, DMF, DMSO.It is preferred, however, that less toxic and environmentally dangeroussolvents such as ethanol or isopropanol are employed. Following the stepof mixing, the metal/linker ratio (i.e. M/L) and water/co-solvent molarratio (where co-solvent is present) are preferred but not limited to bein the ranges M/L=1-15, or more preferably 1-5, andwater/co-solvent=3-100, respectively. The water/co-solvent molar ratiomay be in the range of water/co-solvent=5-100, or 9-100. Thewater/co-solvent ratio may be in the range of 3-80. It will beunderstood that the water/co-solvent ratio in the metal salt/sourcesolution may, in some embodiments, be lower than 3. The temperature ispreferably, but not restricted to be, between 10 and 80° C.; morepreferably 15-65° C. and 20-55° C.

Preferably, the method does not comprise use of environmentally damagingor highly toxic organic solvents (i.e. the co-solvent or a solvent addedto cause precipitation or to wash and purify a precipitate), such asTHF, DMF or DMSO or other non-alcoholic solvents. Preferably the methoddoes not comprise use of methanol (which is known to be of higherflammability and toxicity than, for example, ethanol). In someembodiments, the method does not comprise use of organic solvents.

The time is preferred, but not limited to be, up to 3 days; morepreferably up to 1 day. or preferably 30 min-6 hr to achieve maximumyield. For example, in a method of synthesising MOFs of the formM₂(DHTP)(H₂O)₂.qH₂O, the time is preferably in the range 2-6 hr and in amethod of synthesising MOFs of the formM_(x′)(BTC)_(y′)(OH)_(v′)(H₂O)_(w′), the time is preferably in the range30 min-1 hr, e.g. around 45 mins.

In all cases the product may be recovered by an appropriate meanssuitable for the resulting particle size (for example filtration orcentrifugation), washed in a suitable solvent and dried.

The method may further comprise changing the hydration of the MOF, forexample by heating or otherwise drying the MOF or by washing orotherwise hydrating the MOF.

It has been found that the method may be used to prepare MOFs which arenot known to result from conventional synthetic methods.

Accordingly, the invention extends to an MOF is obtained or obtainableby one or more of said methods as described herein above, in particularan MOF of the formula Zn_(x)Ni_(y)Na_(z)(DHTP)(H₂O)₂.qH₂O; where thevalues of x+y+z=2 or x+y=2 and z=0-8 and q=0-12, or an MOF of the formM_(x′)(BTC)_(y′)(OH)_(v′)(H₂O)_(w′) where x′ is 2-4, y′ is 0.5 to 2, v′is 0 to 2 and w′ is 0-5 or where x′ is 3-4, y′ is 0.8 to 1.2, v′ is 0 to1 and w′ is 0-5.

In a second aspect of the invention there is provided a novel MOF of theformula Zn_(x)Ni_(y)Na_(z)(DHTP)(H₂O)₂.qH₂O; where the values of x+y+z=2or x+y=2 and z=0-8 and q=0-12.

It will be understood that in relation to a given MOF, the value of w,the number of molecules of water of hydration present in the unit cell,will vary depending on the degree of hydration of the MOF.

The above MOF is preferably obtained or is obtainable by one or more ofsaid methods as described herein above.

The MOF, of the present invention may be used for a variety ofapplications, known in the art, for example, the MOFs may be used forgas storage and optional release. Such an application is described indetail in WO2008/020218, incorporated herein by reference, to which theskilled reader is directed.

In a third aspect of the invention, there is provided a MOF of the formM_(x′)(BTC)_(y′)(OH)_(v′)(H₂O)_(w′) where x′ is 1-5, y′ is 0.1 to 5, v′is 0 to 2 and w′ is 0-5. x′ may be in the range of 2-4, or 3-4. y′ maybe in the range from around 0.5 to 2, or 0.8 to 1.2.

The MOF may be of the form M_(x′)(BTC)_(y′)(OH)_(v′)(H₂O)_(w)′ where x′is 3-4, y′ is 0.8 to 1.2, v′ is 0 to 1 and w′ is 0-5.

In some embodiments, x′ is 3-4, y′ is 0.8 to 1.2, v′ is 0 and z′ is 1-5.

M is preferably Ag. The MOF of the third aspect comprises a particularlyhigh proportion of M, i.e. the metal to linker M/BTC ratio.

The MOF is preferably obtained or obtainable by the method of the firstaspect.

The MOF is preferably obtained or obtainable by adding together asuspension of trimesic acid and a basic solution (e.g. sodiumhydroxide), to thereby provide an aqueous solution of a salt of BTC.

The MOF is preferably obtained or obtainable by mixing an aqueoussolution of a salt of BTC with an aqueous solution of a metalsalt/source, for example aqueous silver nitrate.

It has been found that the MOF so obtained has a higher M/BTC ratio thanmaterials prepared by conventional synthetic methods. The higher metal(e.g. silver) content is proposed to be associated with antibacterialactivity. Thus, the invention further extends to use of the MOF of thethird aspect as an antibacterial agent and to an article comprising theMOF of the first aspect. The MOF of the third aspect may form part of acoating formulation, such as a paint or a powder coat comprising the MOFof the third aspect. The article may for example be a fabric (woven ornon-woven) or a plastics material coated or impregnated with the MOF, ora formulation comprising the MOF. The formulation may further comprisesurfactants, fixing agents and other additives known to the skilledreader.

The MOFs of the present invention may also be used in terms ofantimicrobial actions and again this is described in detail and the MOFsmay be modified as described in WO2012/020214, incorporated herein byreference, to which the skilled reader is directed.

The present invention will now be further described by way of exampleand with reference to figures which show:

DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the followingdrawings in which:

FIG. 1 shows XRD data for products prepared from Zn acetate withdifferent co-solvents. The presence of an impurity phase is evident whenno co-solvent is used.

FIG. 2 shows XRD data for products prepared from Zn chloride withdifferent co-solvents. The presence of an impurity phase is evident inall samples.

FIG. 3 shows XRD data for products prepared from Zn nitrate withdifferent co-solvents. The presence of an impurity phase is evident inall samples.

FIG. 4 shows SEM images of Zn_(x)Na_(z)(dhtp)(H₂O)_(g).hH₂O preparedfrom reaction mixtures containing different Zn/linker (Zn/L) andwater/ethanol (W/E) ratios. Top-left Zn/L 1, W/E 94; middle Zn/L 4.2 W/E94; right Zn/L 2.6 W/E 9.7. Bottom-left Zn/L 1 W/E 3.5; right Zn/L 4.2W/E 3.5.

FIG. 5 shows NO release profiles for Zn_(x)Na_(z)(dhtp)(H₂O)_(g).hH₂Osynthesised as per example 3a and with different Zn/linker andwater/ethanol ratios: (a) Zn/L 1 W/E 0.3; (b) Zn/L 1, W/E 94; (c) Zn/L4.2 W/E 3.5; (d) Zn/L 4.2 W/E 94; (e) Zn/L 2.6 W/E 9.7.

FIG. 6 shows XRD patterns of Zn_(x)Na_(z)(dhtp)(H₂O)_(g).hH₂Osynthesised as per example 3a and with different Zn/linker andwater/ethanol ratios: (a) Zn/L 1, W/E 94; (b) Zn/L 1 W/E 3.5; (c) Zn/L4.2 W/E 94; (d) Zn/L 4.2 W/E 3.5 (e) Zn/L 2.6 W/E 9.7.

FIG. 7 shows XRD patterns for Zn_(x)Na_(z)(dhtp)(H₂O)_(g).hH₂O preparedas per example 3a (a) over 1 hr, (b) over 5 hr, (c) over 48 hr and (d)at 50 deg C. over 1 hr.

FIG. 8 shows XRD patterns for Zn_(x)Na_(z)(dhtp)(H₂O)_(g).hH₂O prepared(a) as per example 3b, (b) as per example 3a.

FIG. 9 shows XRD patterns for Zn_(x)Na_(z)(dhtp)(H₂O)_(g).hH₂O prepared(a) as per example 3a, (b) as per example 11a

FIG. 10 shows XRD patterns of Ni_(y)Na_(z)(dhtp)(H₂O)_(g).hH₂Osynthesised as per example 4a with different reaction times asdocumented above. Data show that the phase does not change over time,although crystallinity may be affected.

FIG. 11 shows XRD patterns for Ni_(y)Na_(z)(dhtp)(H₂O)_(g).hH₂Osynthesised as per Example 4b with 1 hr (red) and 4 hr (blue) reactiontimes. The data show that the same phase is obtained.

FIG. 12 shows XRD patterns of MOFs with compositionsZn₂Na_(2.8)(DHTP)(H₂O)₂.qH₂O (top),Zn_(1.47)Ni_(0.53)Na_(0.27)(DHTP)(H₂O)₂.qH₂O (middle) andZn_(1.49)Ni_(0.51)Na_(2.28)(DHTP)(H₂O)₂.qH₂O (bottom)

FIG. 13 shows XRD patterns of MOFs with compositionsZn_(1.88)Ni_(0.12)Na_(3.22)(DHTP)(H₂O)₂.qH₂O (top) andNi₂Na_(2.8)(DHTP)(H₂O)₂.qH₂O (bottom)

FIG. 14 shows XRD patterns for Zn_(x)Na_(z)(dhtp)(H₂O)_(g).hH₂O preparedas per example 6.

FIG. 15 shows XRD patterns for Zn_(x)Na_(z)(dhtp)(H₂O)_(g).hH₂O preparedas per example 7 (blue), 8 (red) and 3a (dark blue)

FIG. 16 shows XRD patterns for Ni_(y)Na_(z)(dhtp)(H₂O)_(g).hH2Osynthesised as per Example 9. Red: order of addition: water, ethanol, Niacetate, NaDHTP. Blue: order of addition—water, Ni acetate, NaDHTP,ethanol.

FIG. 17 a shows XRD pattern of ZnNaDHTP prepared as per example 11b;

FIG. 17 b shows XRD pattern of ZnNaDHTP prepared as per example 13;

FIG. 18 shows XRD pattern of NiNaDHTP prepared as per example 4c;

FIG. 19 shows XRD patterns of NiNaDHTP prepared as per example 15a(bottom) and 15b (top);

FIG. 20 shows powder XRD patterns of the Ag-BTC MOF prepared accordingto examples 16 (middle), 17 (top) and 18 (bottom).

FIG. 21 shows powder XRD patterns of the Ag-BTC MOF prepared accordingto examples 16, 19, 20 and 21 (bottom to top).

FIGS. 22( a)-(c) show powder XRD pattern of the Ag-BTC MOFs preparedaccording to examples 22(a)-(c).

FIG. 23 shows powder XRD patterns of the Ag-BTC MOF prepared accordingto example 23, with crystallisation periods of (top to bottom) 45 min,2, 6, 17, 24 hr.

FIG. 24 shows powder XRD patterns of the Ag-BTC MOF prepared accordingto examples 24 (top) and 25 (bottom).

FIG. 25 shows an powder XRD pattern of the Ag-BTC MOF prepared accordingto example 28.

FIGS. 26( a) and (b) show powder XRD patterns of the Ag-BTC MOF preparedaccording to examples 29 and 30, respectively.

FIG. 27 shows the asymmetric unit cell of the Ag-BTC MOF.

FIG. 28 shows a ball and stick representation of the Ag-BTC along the a-(top) and c-axis (bottom), respectively.

FIG. 29 shows the thermogravimetric analysis of the Ag-BTC of example16.

FIG. 30 shows the thermogravimetric analysis of the Ag-BTC of example29.

FIG. 31 shows the thermogravimetric analysis of the Ag-BTC of example30.

FIG. 32 shows growth inhibition of E. coli NCTC9001.

FIG. 33 shows growth inhibition of P. mirabilis NCTC11938.

FIG. 34 shows growth inhibition of P. aeruginosa (Pa01).

FIG. 35 shows growth inhibition of P. aeruginosa (Pa058).

FIG. 36 shows growth inhibition of S. aureus (DSMZ11729).

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS Examples Relating to MOFsContaining DHTP Linkers Preparation of sodium 2,5-dihydroxyterephthalateExample 1

2,5-dihydroxyterephthalic acid (10 g, 50.5 mmol) was added to 1 molaraqueous sodium hydroxide solution (200 ml) with vigorous stirring. Oncethe acid dissolved, the sodium salt was precipitated by adding in excessof 200 ml of ethanol. The product was filtered and washed in ethanolbefore being refluxed in ethanol (200 ml, 80 C) for 2-3 hr. The solidwas filtered hot, washed with hot ethanol and air dried.

Example 2

2,5-dihydroxyterephthalic acid (10 g, 50.5 mmol) was added to 1 molaraqueous sodium hydroxide solution (200 ml) with vigorous stirring. Oncethe acid dissolved, the sodium salt was recovered by evaporating offwater under vacuum in a rotary evaporator. The product was refluxed inethanol (200 ml, 80 C) for 2-3 hr, filtered hot, washed with hot ethanoland air dried.

Process 1 Example 3a ZnNaDHTP

Sodium 2,5-dihydroxyterephthalate (0.48 g, 2 mmol) was dissolved indeionised (DI) water (15 ml) and the resulting solution was addeddropwise over 3-5 min to a previously prepared aqueous solution of Znacetate dihydrate (1.141 g, 5.2 mmol, in 7.5 ml DI water and 7.5 mlethanol) under vigorous stirring. The mixture was stirred at 20 C for 4hr before the product was recovered by filtration, washed in water (30ml) and air dried.

TABLE 1 Zn source Co-solvent Phase Zn acetate —Zn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O + secondary phase EthanolZn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O MethanolZn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O Iso-propanolZn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O Zn nitrate —Zn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O + secondary phase EthanolZn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O + secondary phase MethanolZn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O + secondary phase Iso-propanolZn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O + secondary phase Zn —Zn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O + secondary phase chloride EthanolZn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O + secondary phase MethanolZn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O + secondary phase Iso-propanolZn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O + secondary phase

Table 1 shows a summary of variations to Example 3a using different Znsources and co-solvent showing that the phase purity depends on Znsource and co-solvent

TABLE 2 Approx Water/ particle ethanol size (SEM) (mol ratio (μm) [seeZn/linker in final images in Yield (mol ratio) solution) Phase FIG. 4 ](g) 1 94 Zn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O 5 0.67 1 3.5Zn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O <1  0.40 2.6 94Zn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O No data 0.53 2.6 9.7Zn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O 5 0.48 2.6 3.5Zn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O No data 0.52 4.2 94Zn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O 5 0.39 4.2 3.5Zn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O <1  0.16

Table 2 shows summary of variations to Example 3a with differentZn/linker and water/ethanol ratios; the data show that solventcomposition helps control particle size and yield

TABLE 3 Temperature Time (deg C.) (hr) Phase Yield (g) 20 1Zn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O 0.48 5 Zn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O0.53 24 Zn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O 0.56 48Zn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O 0.54 50 1Zn_(x)Na_(z)(dhtp)(H₂O)_(g)•hH₂O 0.37

Table 3 shows a summary of variations to Example 3a with differentreaction temperatures.

Example 3b ZnNaDHTP

Sodium 2,5-dihydroxyterephthalate (0.48 g, 2 mmol) was dissolved in DIwater (15 ml) and the resulting solution was added swiftly to apreviously prepared aqueous solution of Zn acetate dihydrate (1.141 g,5.2 mmol, in 7.5 ml DI water and 7.5 ml ethanol) under vigorousstirring. The mixture was stirred at 20 C for 4 hr before the productwas recovered by filtration, washed in water (30 ml) and air dried.

Example 4a NiNaDHTP

Sodium 2,5-dihydroxyterephthalate (0.48 g, 2 mmol) was dissolved in DIwater (15 ml) and the resulting solution was added dropwise over 3-5 minto a previously prepared aqueous solution of Ni acetate dihydrate (1.294g, 5.2 mmol, in 7.5 ml DI water and 7.5 ml ethanol) under vigorousstirring. The mixture was stirred at 20 C for 7 hr before the productwas recovered by filtration, washed in water (30 ml) and air dried.

TABLE 4 Temperature Time (deg C.) (hr) Phase Yield (g) 20 1Ni_(y)Na_(z)(dhtp) (H₂O)_(g)•hH₂O 0.34 20 2 Ni_(y)Na_(z)(dhtp)(H₂O)_(g)•hH₂O 0.42 20 4 Ni_(y)Na_(z)(dhtp) (H₂O)_(g)•hH₂O 0.46 20 7Ni_(y)Na_(z)(dhtp) (H₂O)_(g)•hH₂O 0.52 20 18 Ni_(y)Na_(z)(dhtp)(H₂O)_(g)•hH₂O 0.58 20 24 Ni_(y)Na_(z)(dhtp) (H₂O)_(g)•hH₂O 0.61 20 28Ni_(y)Na_(z)(dhtp) (H₂O)_(g)•hH₂O 0.58

Table 4 shows a summary of variations to Example 4a with differentreaction times. The data show that the formation of the Ni end-member isgenerally slower than that for the Zn end-member—taking approx. 20 hr toreach maximum yield at 20 C.

Example 4b NiNaDHTP

Sodium 2,5-dihydroxyterephthalate (0.48 g, 2 mmol) was dissolved in DIwater (15 ml) and the resulting solution was added dropwise over 3-5 minto a previously prepared aqueous solution of Ni acetate dihydrate (1.294g, 5.2 mmol, in 7.5 ml DI water and 7.5 ml ethanol) under vigorousstirring. The mixture was stirred at 50 C for 4 hr before the productwas recovered by filtration, washed in water (30 ml) and air dried.

TABLE 5 Temperature Time (deg C.) (hr) Phase Yield (g) 50 1Ni_(y)Na_(z)(dhtp) (H₂O)_(g)•hH₂O 0.52 4 Ni_(y)Na_(z)(dhtp)(H₂O)_(g)•hH₂O 0.63 6 Ni_(y)Na_(z)(dhtp) (H₂O)_(g)•hH₂O 0.68

Table 5 shows a summary of variations to Example 4b with differentreaction times showing that the process time can be reduced to a fewhours by raising the temperature slightly to 50 C.

TABLE 6 Water/co- solvent (mol Ni/linker ratio in final (mol ratio)solution) Phase Yield (g) 1.4 9.7 Ni_(y)Na_(z)(dhtp) (H₂O)_(g)•hH₂O 0.772 9.7 Ni_(y)Na_(z)(dhtp) (H₂O)_(g)•hH₂O 0.62 2.6 9.7 Ni_(y)Na_(z)(dhtp)(H₂O)_(g)•hH₂O 0.68 3.2 9.7 Ni_(y)Na_(z)(dhtp) (H₂O)_(g)•hH₂O 0.50

Table 6 shows a summary of variations to Example 4b with different Ni/Nalinker ratios.

Example 4c NiNaDHTP

2,5-dihydroxyterephthalic acid (2.02 g, 10.2 mmol) was added to aqueoussodium hydroxide (30 ml, 1.017M). The resulting solution was addeddropwise over 15 min to a solution of Ni acetate dihydrate (5.10 g, 20.4mmol) in DI water (30 ml). The mixture was stirred vigorously at 50 Cfor 6 hr before the product was recovered by filtration, washed in water(60 ml) and air dried.

Example 5 ZnNiNaDHTP

Sodium 2,5-dihydroxyterephthalate (0.48 g, 2 mmol) was dissolved in DIwater (15 ml) and the resulting solution was added dropwise over 3-5 minto a previously prepared aqueous solution of Ni acetate dihydrate (0.129g, 0.52 mmol) and Zn acetate dihydrate (1.027 g, 0.47 mmol) in 7.5 ml DIwater and 7.5 ml ethanol, under vigorous stirring. The mixture wasstirred at 20 C for 4 hr before the product was recovered by filtration,washed in water (30 ml) and air dried.

TABLE 7 Zn/Ni Average mol Approx particle % Composition size NO releasedused in of product (SEM) (mmol/g)/ reaction (EDX) (μm) time 100/0 Zn₂Na_(2.8)(DHTP)(H₂O)₂•qH₂O 5 0.05/12 hr  90/10Zn_(1.88)Ni_(0.12)Na_(3.22)(DHTP)(H₂O)₂•qH₂O 5 0.3/18 hr 80/20Zn_(1.77)Ni_(0.23)Na_(3.93)(DHTP)(H₂O)₂•qH₂O 3 70/30Zn_(1.47)Ni_(0.53)Na_(0.27)(DHTP)(H₂O)₂•qH₂O <1 0.3/45 hr 60/40Zn_(1.49)Ni_(0.51)Na_(2.28)(DHTP)(H₂O)₂•qH₂O <1 0.7/17 hr

Table 7 shows a summary of variations to Example 5 showing how particlesize and NO release profile can be tuned by varying the Zn/Ni ratio

Process 2 Example 6 ZnNaDHTP

Zn acetate dihydrate (1.141 g, 5.2 mmol), DI water (22.5 ml), ethanol(7.5 ml) and sodium 2,5-dihydroxyterephthalate (0.48 g, 2 mmol), weremixed together. The mixture was stirred vigorously at 20 C for 4 hrbefore the product was recovered by filtration, washed in water (30 ml)and air dried.

Example 7 ZnNaDHTP

Zn acetate dihydrate (3.5 g, 16 mmol), DI water (22.5 ml), ethanol (7.5ml) and sodium 2,5-dihydroxyterephthalate (1.49 g, 6.2 mmol), were mixedtogether. The mixture was stirred vigorously at 20 C for 4 hr before theproduct was recovered by filtration, washed in water (30 ml) and airdried.

Example 8 ZnNaDHTP

Zn acetate dihydrate (7 g, 0.032 mol), DI water (22.5 ml), ethanol (7.5ml) and sodium 2,5-dihydroxyterephthalate (2.97 g, 0.012 mol), weremixed together. The mixture was stirred vigorously at 20 C for 4 hrbefore the product was recovered by filtration, washed in water (30 ml)and air dried.

Example 9 NiNaDHTP

Ni acetate dihydrate (1.027 g, 0.47 mmol), DI water (22.5 ml), ethanol(7.5 ml) and sodium 2,5-dihydroxyterephthalate (0.48 g, 2 mmol), weremixed together. The mixture was stirred vigorously at 20 C for 4 hrbefore the product was recovered by filtration, washed in water (30 ml)and air dried.

Process 3 Example 10 ZnNaDHTP

a) 2,5-dihydroxyterephthalic acid (0.51 g, 2.6 mmol) was added toaqueous sodium hydroxide (15 ml, 0.67M). A solution of Zn acetatedihydrate (1.141 g, 5.2 mmol) in DI water (7.5 ml) and ethanol (7.5 ml)was added dropwise to the resulting solution over 3-5 min with stirring.The mixture was stirred vigorously at 20 C for 4 hr before the productwas recovered by filtration, washed in water (30 ml) and air dried.

b) 2,5-dihydroxyterephthalic acid (0.51 g, 2.6 mmol) was added toaqueous sodium hydroxide (15 ml, 0.52M). A solution of Zn acetatedihydrate (1.141 g, 5.2 mmol) in DI water (7.5 ml) and ethanol (7.5 ml)was added dropwise to the resulting solution over 3-5 min with stirring.The mixture was stirred vigorously at 20 C for 4 hr before the productwas recovered by filtration, washed in water (30 ml) and air dried.

Example 11a ZnNaDHTP

Zn acetate dihydrate solution (1.141 g, 5.2 mmol, in 7.5 ml DI water and7.5 ml ethanol) was added dropwise over 3-5 min to a previously preparedsolution of sodium 2,5-dihydroxyterephthalate (0.48 g, 2 mmol) in DIwater (15 ml) under vigorous stirring. The mixture was stirred at 20 Cfor 4 hr before the product was recovered by filtration, washed in water(30 ml) and air dried.

Example 11b ZnNaDHTP

2,5-dihydroxyterephthalic acid (1.03 g, 5.2 mmol) was added to aqueoussodium hydroxide (30 ml, 0.35M) and heated to 60 C. To the resultingsolution was added Zn acetate dihydrate (2.96 g, 13.5 mmol) in DI water(15 ml) and ethanol (15 ml), dropwise over 25 min, with stirring. Themixture was stirred vigorously at 60 C for 4 hr before the product wasrecovered by filtration, washed in water (30 ml) and air dried

Example 12 ZnNaDHTP

2,5-dihydroxyterephthalic acid (0.39 g, 2 mmol), sodium hydroxide (0.16g, 4 mmol) and then Zn acetate dihydrate (1.141 g, 5.2 mmol) wasdissolved in DI water (22.5 ml) and ethanol (7.5 ml) with stirring. Themixture was stirred vigorously at 20 C for 4 hr before the productrecovered by filtration, washed in water (30 ml) and air dried.

Example 13 ZnNaDTHP; Higher Concentration Synthesis

2,5-dihydroxyterephthalic acid (2.3 g, 11.8 mmol) was dissolved inaqueous sodium hydroxide (24 ml, 2M) at 60 C. A solution of Zn acetatedihydrate (8 g, 36.5 mmol) in DI water (13 ml) and ethanol (4.3 ml),also at 60 C, was added dropwise to the resulting solution over 3-5 minwith stirring. The mixture was stirred vigorously at 60 C for 3 hrbefore the product was recovered by filtration, washed in water (30 ml)and air dried.

Example 14 NiNaDHTP

2,5-dihydroxyterephthalic acid (2.02 g, 10.2 mmol) was added to aqueoussodium hydroxide (30 ml, 1.017M). To the resulting solution Ni acetatedihydrate (5.10 g, 20.4 mmol) in DI water (30 ml) was added dropwiseover 15 min. The mixture was stirred vigorously at 50 C for 6 hr beforethe product was recovered by filtration, washed in water (60 ml) and airdried.

Example 15 NiNaDHTP

a) 2,5-dihydroxyterephthalic acid (0.51 g, 2.6 mmol) was added toaqueous sodium hydroxide (15 ml, 0.67M). A solution of Ni acetatedihydrate (1.296 g, 5.2 mmol) in DI water (15 ml) was added dropwise tothe resulting solution over 3-5 min with stirring. The mixture wasstirred vigorously at 50 C for 6 hr before the product was recovered byfiltration, washed in water (30 ml) and air dried.

b) 2,5-dihydroxyterephthalic acid (0.51 g, 2.6 mmol) was added toaqueous sodium hydroxide (15 ml, 0.52M). A solution of Ni acetatedihydrate (1.296 g, 5.2 mmol) in DI water (15 ml) was added dropwise tothe resulting solution over 3-5 min with stirring. The mixture wasstirred vigorously at 50 C for 6 hr before the product was recovered byfiltration, washed in water (30 ml) and air dried.

Examples Relating to MOFs Containing BTC Linkers

Materials were prepared according to three general synthetic procedures(A)-(C) described below.

Synthesis Procedure (A)

A basic solution (such as aqueous sodium hydroxide, potassium hydroxide,or organic bases such as ammonia, trimethylamine, triethylamine orsimilar) is added to a suspension of trimesic acid in water (preferablydistilled or de-ionised) until the desired pH is achieved at which thesuspended trimesic acid dissolves (typically pH 7 and above, dependingon the basic solution used). A solution of a metal salt is then added atthe required rate under brisk stirring. The invention is not limited toa particular metal salt or salts, or solvent. For the preparation ofAg-BTC MOFs, silver nitrate in distilled water is preferred, in order tominimise use of organic solvents. On mixing of the two solutions at atemperature typically in the range 2-100° C. or 18-30° C., a precipitateis formed which is recovered after a period of time (e.g. 1 min to 2days, or more preferably in the range 20-120 min). Precipitate isrecovered by any suitable method, (e.g. filtration). In an optionalpurification step, the product is washed with one or more solvents (e.g.water then ethanol), and air dried. Examples 16-25 of preparing a Ag-BTCMOF by method (A) are set out below.

Example 16

1M sodium hydroxide solution was added dropwise to a suspension oftrimesic acid (1.007 g, 4.8 mmol) in distilled 75 ml water to aphenolphthalein end-point (pH7). To this was added a solution of silvernitrate (3.5 equivalents) in 12.5 ml distilled water, dropwise withstirring at 20° C. After 45 min the product was recovered by filtration,washed with distilled water, then ethanol and air dried.

Example 17

1M sodium hydroxide solution was added dropwise to a suspension oftrimesic acid (1.007 g, 4.8 mmol) in distilled 75 ml water to achieve pH10. To this was added a solution of silver nitrate (3.5 equivalents) in12.5 ml distilled water, dropwise with stirring at 20° C. After 45 minthe product was recovered by filtration, washed with distilled water,then ethanol and air dried.

Example 18

1M sodium hydroxide solution was added dropwise to a suspension oftrimesic acid (1.007 g, 4.8 mmol) in distilled 75 ml water to achieve pH6. To this was added a solution of silver nitrate (3.5 equivalents) in12.5 ml distilled water, dropwise with stirring at 20° C. After 45 minthe product was recovered by filtration, washed with distilled water,then ethanol and air dried.

Example 19

1M sodium hydroxide solution was added dropwise to a suspension oftrimesic acid (1.007 g, 4.8 mmol) in distilled 75 ml water to aphenolphthalein end-point. To this was added a solution of silvernitrate (3.5 equivalents) in 12.5 ml distilled water, quickly withstirring at 20° C. After 45 min the product was recovered by filtration,washed with distilled water, then ethanol and air dried.

Example 20

1M sodium hydroxide solution was added dropwise to a suspension oftrimesic acid (1.007 g, 4.8 mmol) in distilled 75 ml water to aphenolphthalein end-point. This solution was added to a solution ofsilver nitrate (3.5 equivalents) in 12.5 ml distilled water, dropwisewith stirring at 20° C. After 45 min the product was recovered byfiltration, washed with distilled water, then ethanol and air dried.

Example 21

1M sodium hydroxide solution was added dropwise to a suspension oftrimesic acid (1.007 g, 4.8 mmol) in distilled 75 ml water to aphenolphthalein end-point. This solution was added to a solution ofsilver nitrate (3.5 equivalents) in 12.5 ml distilled water, quicklywith stirring at 20° C. After 45 min the product was recovered byfiltration, washed with distilled water, then ethanol and air dried.

Example 22a

1M sodium hydroxide solution was added dropwise to a suspension oftrimesic acid (1.007 g, 4.8 mmol) in distilled 75 ml water to aphenolphthalein end-point. To this was added a solution of silvernitrate (3.5 equivalents) in 12.5 ml distilled water, dropwise withstirring at 60° C. After 45 min the product was recovered by filtration,washed with distilled water, then ethanol and air dried.

Example 22b

Trimesic acid (5 g, 23.8 mmol) was dissolved in aqueous sodium hydroxide(71.4 ml, 1M) under reflux. Once dissolved, the solution was cooled to60° C. before a solution of silver nitrate (12 g, 70.6 mmol) in water(100 ml) was added. After stirring at 60° C. for 4 hr, the product wasrecovered by filtration, washed with distilled water, then ethanol andair dried. Approximate product composition of material synthesised inthis manner was found to be in the range Ag₂₋₄(BTC)_(0.5-2)0.1-3H₂O (asdetermined from single crystal XRD and TGA studies). Powder XRD data(FIG. 22( b)) and single crystal XRD data indicate that the material isa new phase and differs from the materials synthesised at a lowertemperature (examples 22a and 22c).

Example 22c

Trimesic acid (5 g, 23.8 mmol) was dissolved in aqueous sodium hydroxide(71.4 ml, 1M) under reflux. Once dissolved, the solution was cooled toroom temperature before a solution of silver nitrate (12 g, 70.6 mmol)in water (100 ml) was added. After stirring at room temperature for 4hr, the product was recovered by filtration, washed with distilledwater, then ethanol and air dried.

Example 23

1M sodium hydroxide solution was added dropwise to a suspension oftrimesic acid (1.007 g, 4.8 mmol) in distilled 75 ml water to aphenolphthalein end-point. To this was added a solution of silvernitrate (3.5 equivalents) in 12.5 ml distilled water, dropwise withstirring at 20° C. After 20 min, 1 hr, 5 hr. 16 hr and 24 hr the productwas recovered by filtration, washed with distilled water, then ethanoland air dried.

Example 24 1:14

1M sodium hydroxide solution was added dropwise to a suspension oftrimesic acid (0.503 g, 2.4 mmol) in distilled 75 ml water to aphenolphthalein end-point. To this was added a solution of silvernitrate (14 equivalents) in 50 ml distilled water, dropwise withstirring at 20° C. After 45 min the product was recovered by filtration,washed with distilled water, then ethanol and air dried.

Example 25 1:1

1M sodium hydroxide solution was added dropwise to a suspension oftrimesic acid (1.131 g, 5.4 mmol) in distilled 75 ml water to aphenolphthalein end-point. To this was added a solution of silvernitrate (1 equivalent) in 12.5 ml distilled water, dropwise withstirring at 20° C. After 45 min the product was recovered by filtration,washed with distilled water, then ethanol and air dried.

Example 26

Trimesic acid (5 g, 23.8 mmol) was dissolved in NaOH (1M, 74.1 mL) andwater (218.8 mL) at 30° C. Once dissolved, the pH was adjusted to 7using nitric acid before silver nitrate (12 g, 70.6 mmol) in water (100mL) was charged rapidly to the flask. After stirring at 30° C. for 2.5hr, the product was recovered by filtration, washed with distilledwater, then ethanol and air dried.

Example 27 Slower Addition Rate

Trimesic acid (5 g, 23.8 mmol) was dissolved in NaOH (1M, 74.1 mL) andwater (218.8 mL) at 30° C. Once dissolved, the pH was adjusted to 7using nitric acid before silver nitrate (12 g, 70.6 mmol) in water (100mL) was charged over 10 min to the flask. After stirring at 30° C. for2.5 hr, the product was recovered by filtration, washed with distilledwater, then ethanol and air dried.

XRPD data indicate that examples 26 and 27 produced the same phase asexamples 16, 19, 20, 21, 22(a), 22(c), 23, 24, 25, 29 and 30.

Synthesis Procedure (A′)

A MOF synthesised according to procedure (A) is dried and then heated inwater with stirring. The resulting MOF is then coiled, filtered anddried.

Example 28

10 g of the dried product from example 22(b) was heated in water at 70°C., with stirring, for 12 hr before being cooled, filtered and dried.

Approximate product composition of material synthesised in this mannerwas found to be in the range Ag₂₋₄(BTC)_(0.5-2)0.1-2H₂O (as determinedfrom single crystal XRD and TGA studies). Powder XRD data (FIG. 25) andsingle crystal XRD data indicate that the material is a new phase anddiffers from the materials synthesised in examples 22(a)-(c).

Synthesis Procedure (B)

A suspension of trimesic acid in water (preferably distilled ordeionised) is neutralised with base (for example, but not limited to,sodium hydroxide) until the desired pH is sufficiently high for thetrimesic acid to dissolve. Once the acid has dissolved, the water isevaporated to leave a trimesate salt residue, which is purified byrefluxing in a suitable solvent (e.g. ethanol). The salt is thenrecovered by an appropriate means such as filtration.

An aqueous solution of the trimesate salt is then prepared and asolution of a metal salt in an appropriate solvent (e.g. silver nitratein water) is added, as described above in relation to method A, and theresulting MOF recovered and washed with water and ethanol. Example 26 ofpreparing a Ag-BTC MOF by method (B) is set out below.

Example 29

3.5 equiv of sodium hydroxide was added to a suspension of 1 equivtrimesic acid in distilled water with stirring. The trimesic acid slowlydissolved and the solution stirred for a further 30 minutes and thewater evaporated. The residue was refluxed in ethanol for 30 minutes andrecovered by filtration and air dried.

A solution of silver nitrate (3 equivalents) in distilled water wasadded dropwise to an aqueous solution of the sodium salt of trimesicacid with stirring. The product was recovered by filtration, washed withdistilled water, then ethanol and air dried.

Synthesis Procedure (C)

A single crystal Ag-BTC MOF sample was prepared as follows:

Example 30

A solution of the sodium salt of trimesic acid (69.0 mg, 0.2 mmol) indistilled water (5 ml) was placed into the bottom of a test tube, towhich distilled water (5 ml) was carefully layered on top and then asolution of silver nitrate (102.0 mg, 0.6 mmol, 3 equiv.) in distilledwater (5 mL). The resultant layered solution was placed in the dark tocrystallise for 4 days. The product was recovered by filtration, washedwith distilled water, then ethanol and air dried. Small single crystalswere visible.

Experimental Powder X-Ray Diffraction

Data were collected on a Panalytical Empyrean diffractometer operatingCu Kα₁ radiation monochromated with a curved Ge (111) crystal inreflectance mode.

Single Crystal X-Ray Diffraction

Data were collected on beamline 11.3.1 at the Advanced Light Source,Berkeley, Calif. The structure was solved by direct methods (SHELXS97)and refined by full-matrix least-squares analysis (SHELXL-97).

Thermal Analysis

Data were collected on a TA Instruments SDT 2960. Samples were heated inan alumina crucible at a rate of 10° C. min⁻¹ to a maximum temperatureof 900° C. in a flowing atmosphere of air.

Elemental Analysis

Data were collected on a Carlo Erba Flash 2000 Organic ElementalAnalyser.

Antimicrobial Susceptibility

Antimicrobial susceptibility testing to determine the growth inhibitionby the test items was carried out using modifications of the followingClinical and Laboratory Standards Institute (CLSI) Approved Standards:

Methods for Dilution Antimicrobial Susceptibility Tests for Bacteriathat Grow Aerobically (M07-A8)

Antimicrobial susceptibility testing using the above CLSI ApprovedStandards requires test antimicrobial materials to be in an aqueoussolution. As MOFs are solid disks it was not possible to follow thesemethods precisely. The MOFs were not optically transparent and thereforedid not permit kinetic analysis of microbial growth by changes inoptical density. Therefore, the above CLSI protocol was adapted tomonitor microbial metabolic activity using 10% (v/v) resazurin (Alamarblue; a cell viability indicator) which detected growth by changes influorescence rather than optical density. Changes in fluorescence weredetermined using a BioTek Synergy HT Multi-Mode Microplate Reader.

The following bacterial strains were tested to determine antibacterialactivity

-   -   E. coli NCTC9001    -   P. mirabilis NCTC11938    -   S. aureus DSMZ11729    -   P. aeruginosa Pa01    -   P. aeruginosa Pa058

Analytical Data

Powder X-Ray Diffraction

Powder X-ray diffraction data (FIGS. 20-26) show that the Ag-BTCmaterials made by the procedures A-C are new phases which differ(discussed above) from Ag BTC MOFs described in the literature. Inaddition, there are no similar materials present within theInternational Centre for Diffraction Data, Powder Diffraction File(“ICDD PDF”) database. These data also confirm that the materialsprepared by the different synthesis methods of procedures A-C containthe same phases.

Example 22a was prepared at an elevated temperature of 60° C. Thecontrast of the corresponding powder XRD pattern (FIG. 22( a) to thepatters shown in FIG. 20, for example, demonstrate the temperaturesensitivity of the synthesis. This is further demonstrated by thedifferences between each of examples 22(a)-(c).

The powder diffraction pattern of example 30 differs from that of theprevious examples by the addition of intense diffractions peaks(quantity in brackets) at approximately 9.4, 12.3, 18.6 (2), 28.2 (2),36.8 (multiple) and 37.6 (2) ° 20. These peaks result from an impurityphase. Peaks common to samples 16-26 are also present.

Single Crystal X-Ray Diffraction

The material of example 27 was found to crystallise in the triclinicspace group P-1, details of the crystal structure and refinementinformation are presented in Table 1.

TABLE 1 Crystal data and structure refinement for AgBTC. Identificationcode AgBTC Empirical formula Ag₁₄(C₉H₃O₆)₄(OH)₂ Formula weight 2372.65Temperature 150(2) K Wavelength 0.77490 Å Crystal system, space groupTriclinic, P-1 Unit cell dimensions a = 8.707(2) Å α = 102.559(4)° b =13.950(3) Å β = 99.157(3)° c = 19.756(5) Å γ = 100.934(4)° Volume2249.0(9) Å³ Z, Calculated density 2, 3.504 Mg/m³ Absorption coefficient6.039 mm⁻¹ F(000) 2192 Crystal size 0.01 × 0.01 × 0.05 mm Theta rangefor data collection 2.79 to 34.57° Limiting indices −12 <= h <= 12, −20<= k <= 19, −28 <= I <= 28 Reflections collected/unique 32843/13747[R(int) = 0.0685] Completeness to theta = 34.57 92.90% Refinement methodFull-matrix least-squares on F² Data/restraints/parameters 13747/140/365Goodness-of-fit on F²   1.166 Final R indices [I > 2sigma(I)] R₁ =0.2468, wR₂ = 0.5677 R indices (all data) R₁ = 0.2916, wR₂ = 0.5854Largest diff. peak and hole 9.820 and −22.325e · Å⁻³

FIG. 27 shows the asymmetric unit contains fourteen silver (I) ions,four molecules of trimesate and two hydroxyls to give an overallchemical formula of Ag₁₄(C₉H₃O₆)₄(OH)₂. This produces athree-dimensional connected material with small pores along the a-axisthat contain protruding hydroxyl groups (FIG. 28).

Chemical Composition

TABLE 2 Results of CHN elemental analysis. C (wt %) H (wt %) N (wt %)(1) (2) (1) (2) (1) (2) Example 1 18.83 18.97 1.25 1.17 <0.1 <0.1Example 2 19.32 19.19 1.07 1.16 <0.1 <0.1 Example 3 18.95 19.05 1.081.14 <0.1 <0.1 Theoretical 18.22 0.59 0.00

The refined structure obtained from single crystal X-ray diffraction isalso consistent with the results obtained from the CHN elementalanalysis (Table 2). However, there are differences in thethermogravimetric analysis (TGA), FIGS. 29-31, which explain the smalldiscrepancies from the CHN elemental analysis. The TGA data infer thatthere are volatiles present within the small pores of the material(water or ethanol from the synthesis method) and this could becontributing to the differences observed in both the TGA and elementalanalysis.

Thermal analysis revealed a mass loss between ambient to −120° C.ranging from 4.09-9.42 wt % and a further mass loss between 120° C. and400° C. ranging from 34.90-37.39 wt %. The first mass loss is attributedto volatiles (water and/or ethanol) and the second to trimesate with asolid residue ranging from 55.39-61.72 wt %. The discrepancies could bedue to the different synthetic routes and therefore represents a windowof chemical composition for this novel material.

Microbial Susceptibility Testing

E. coli (NCTC9001).

The results in FIG. 32 demonstrate that the above material inhibitsmetabolic activity of E. coli (NCTC9001) after 20 hours incubation at37° C. under aerobic conditions.

P. mirabilis (NCTC11938).

The results in FIG. 14 demonstrate that the above material inhibits themetabolic activity of P. mirabilis (NCTC11938) after 20 hours incubationat 37° C. under aerobic conditions.

P. aeruginosa (Pa01).

The results in FIG. 34 demonstrate that the above material inhibits themetabolic activity of P. aeruginosa (Pa01) after 20 hours incubation at37° C. under aerobic conditions.

P. aeruginosa (Pa058).

The results in FIG. 35 demonstrate that the above material inhibits themetabolic activity of P. aeruginosa (Pa058) after 20 hours incubation at37° C. under aerobic conditions.

S. aureus (DSMZ11729).

The results in FIG. 36 demonstrate that the above material inhibits themetabolic activity of S. aureus (DSMZ11729) after 20 hours incubation at37° C. under aerobic conditions.

These data show that the novel silver trimesate MOF material of thepresent invention shows excellent antibacterial activity towards severalstrains of bacterium. It is proposed that the antibacterial propertiesmay be related to the comparatively high silver content (in relation topreviously reported Ag-MOFs).

REFERENCES

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1. A method of synthesizing a metal organic framework having the formM_(x)(L)_(y)(OH)_(v)(H₂O)_(w) wherein; M is a metal or metals; L is abenzene polycarboxylate linker; and x is in a range from 1-10, y is in arange from 0.1-3, v is in a range from 0-2 and w is in a range from0-14; the method comprising the step of providing a salt of the benzenepolycarboxylate linker or an aqueous solution thereof; and mixing thesalt of the benzene polycarboxylate linker or an aqueous solutionthereof with a solution of a metal salt at a temperature between 0° C.and 100° C., to thereby obtain said metal organic framework.
 2. A methodaccording to claim 1, comprising providing a water soluble salt of thebenzene polycarboxylate linker.
 3. A method according to claim 1,wherein the benzene polycarboxylate linker is 2,5-dihydroxyterephthalateor 1,3,5-benzene tricarboxylate.
 4. A method according to claim 1,wherein M is one or more of metals selected from the group consisting ofZn, Ni, Mn, Mg, Ag, Cu, and Na.
 5. A method according to claim 3,wherein the metal organic framework is in the form ofM₂M′_(z)(DHTP)(H₂O)₂.qH₂O; wherein q is in a range from 0-12, z is in arange from 0-8; and M is one or more metals selected from the groupconsisting of Zn, Ni, Mn, Mg, Ag, Cu, and Na, and M′ is a further metalselected from, the group consisting of Zn, Ni, Mn, Mg, Ag, Cu, and Na.6. A method according to claim 3, wherein the metal organic framework isin the form of M_(x′)(BTC)_(y′)(OH)_(v′)(H₂O)_(w′); x′ is in a rangefrom 1-5, y′ is in a range from 0.1 to 3, v′ is in a range from 0 to 2and w′ is in a range from 0-5.
 7. A method according to claim 6, whereinx′ is in a range from 2-4 and y′ is in a range from 0.5 to
 2. 8. Amethod according to claim 6, wherein M is Ag.
 9. A method according toclaim 1, wherein the salt of the benzene polycarboxylate linker or anaqueous solution thereof in the providing step is prepared by combininga conjugate acid or salt of the benzene polycarboxylate linker and abase.
 10. A method according to claim 9, wherein the benzenepolycarboxylate linker or an aqueous solution thereof in the providingstep is prepared by adding a solution or suspension of the conjugateacid or salt of the benzene polycarboxylate linker to a sodium hydroxidesolution, to thereby provide an aqueous solution of a salt of thebenzene polycarboxylate linker.
 11. A method according to claim 1,comprising providing an aqueous solution of a salt of the benzenepolycarboxylate linker, and vigorously mixing the aqueous solution witha solution of the metal salt.
 12. A method according to claim 1,comprising providing a water soluble salt of the benzene polycarboxylatelinker, and vigorously mixing the water soluble salt of the benzenepolycarboxylate linker, the metal salt, water and optionally aco-solvent directly in a single vessel.
 13. A method according to claim1, wherein the metal to polycarboxylate linker molar ratio M/L is in arange from 1-5.
 14. A method according to claim 1, wherein thetemperature is within a range selected from the group consisting ofbetween 10° C. and 80° C.; or between 15° C. and 65° C.; and between 20°C. and 55° C.
 15. A metal organic framework of the formulaZn_(x)Ni_(y)Na_(z)(DHTP)(H₂O)₂.qH₂O; where the sum of the values ofx+y+z=2, or the sum of x+y=2 and z has a value in a range from 0-8; andq has a value in a range from 0-12.
 16. A metal organic framework of theform M_(x′)(BTC)_(y′)(OH)_(v′)(H₂O)_(w′) where x′ has a value in a rangefrom 1-5, y′ has a value in a range from 0.1 to 3, v′ has a value in arange from 0 to 2 and w′ has a value in a range from 0.5.
 17. A metalorganic framework according to claim 16, wherein x′ is in a range from2-4 and y′ is in a range from 0.5 to
 2. 18. A metal organic frameworkaccording to claim 16, wherein x′ is in a range from 3-4, y′ is in arange from 0.8 to 1.2, v′ is 0 and z′ is in a range from 1-5.
 19. Ametal organic framework according to claim 16, wherein M is Ag.
 20. Ametal organic framework according to claim 16, obtained or obtainable bya method comprising adding together a suspension of trimesic acid and abasic solution to thereby provide an aqueous solution of a salt of1,3,5-benzene tricarboxylate.
 21. A metal organic framework according toclaim 16, obtained or obtainable by mixing an aqueous solution of a saltof 1,3,5-benzene tricarboxylate with an aqueous solution of silvernitrate.
 22. An antimicrobial formulation comprising the metal organicframework of claim 16 and one or more additives.